The present invention relates to a card identifying apparatus that identifies the validity of cards such as, for example, bills, coupons, gift certificates and the like having the exchange value (economic value) for various kinds of products and service.
Generally, the cards such as bills, coupons, gift certificates and like are provided with various anti-counterfeit measures to prevent forgery. For example, as one of such anti-counterfeit measures, it is carried out providing a microprint (extremely fine characters, pattern and the like), reading the information of this microfilm to compare with genuine data, and thereby identifying (authentication judgment) the validity. In other words, such a microprint has fine line widths, and thereby is known to exhibit a specific pattern (moire fringes; moire pattern) by interference of light, and it is carried out obtaining the moire fringes (moire pattern) to compare with authorized data, and thereby identifying the validity of the card.
For example, Japanese Laid-Open Patent Publication No. 2004-78620 discloses techniques for forming a hidden pattern comprised of a parallel line tint in an information storage member as the card, and irradiating the hidden pattern using a light source, while detecting the reflected light via a confirmation pattern (a parallel line pattern for confirmation is formed) by a photosensor. In this case, the photosensor is capable of sensing a specific moire pattern by interference of the parallel light tint of the hidden pattern and the parallel light tint of the confirmation pattern, and an authentication judgment on the card is made by comparing the moire pattern with a standard pattern.
Further, Japanese Laid-Open Patent Publication No. H07-306964 discloses techniques for applying light to a card with a microprint using a stroboscopic lighting apparatus, and detecting the reflected light in image detecting means (area sensor) via moire fringe generating means (grid plate) for generating moire fringes. More specifically, moire fringes occur by the reflected light from the microprint passing through the grid plate, are detected by the area sensor that is the image detecting means, and judged to be good when the intensity of the frequency component fm exceeds beforehand set threshold Th, while being judged to be not good when the frequency component fm does not exceed the threshold.
In the card identifying apparatus provided with the above-mentioned authentication judgment techniques, to improve the authentication judgment accuracy, there is a case of using a sensor with a higher resolution than that of the currently used sensor. In such a case, in the techniques as described in Patent Documents 1 and 2, the need arises for surveying again a filter (grid plate) with a confirmation pattern to generate a moire pattern, and manufacturing again the filter (grid plate) corresponding to the survey, and it becomes difficult to suppress increases in the cost.
Accordingly, a card identifying apparatus is required that enables an authentication judgment to be made using a microprint formed in the card, while suppressing increases in the cost.